Wheelchair Ramp Slope Calculator
Enter ramp rise and horizontal run in the same unit to calculate grade, angle, and ratio, plus the run needed for a 1:12 geometric reference.
Written and checked by TheToolNet Editorial Team · Last reviewed: September 20, 2026 · Editorial method
Check wheelchair ramp slope
What does 1:12 mean?
A 1:12 slope means 12 units of horizontal run for each unit of vertical rise: 30 inches of rise needs 360 inches of run before landings are considered. It equals an 8.333% grade.
Geometry is not a full compliance check
The US 2010 ADA Standards section 405 generally limits ramp runs to 1:12, with separate rules for cross slope, rise, width, landings, handrails, edge protection, and existing-site exceptions. Local rules and project conditions may differ. Confirm the complete design with the authority having jurisdiction.
Source: US Department of Justice, 2010 ADA Standards.
Need a general conversion?
Use the slope percentage calculator for angle, ratio, road, stair, or mountain-grade conversions.